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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28069 results found.

  1. GRB 060510B: MDM Observations and candidate OT
  2. GRB 060510B: Swift detection of a burst
  3. GRB 060510: Swift detection of a burst with optical transient
  4. GRB060507: optical afterglow detection
  5. GRB060502B: improvement in the XRT afterglow position
  6. GRB 060507: BART limit
  7. GRB 060507: Swift/UVOT Upper Limits
  8. GRB 060507: Swift XRT Team Refined Analysis
  9. GRB 060507: MDM Optical Upper Limit
  10. GRB060507: Swift XRT position
  11. GRB 060507: Swift detection of a burst
  12. GRB060505: Swift/UVOT Observations
  13. GRB 060505: Swift XRT Team Refined Analysis
  14. GRB 060306: Further Analysis of SOAR and APO NIR Observations
  15. GRB 060505: Swift XRT afterglow canditate position
  16. GRB 060502b: Second epoch Gemini observations
  17. GRB 060505: Swift-BAT detection of a weak burst
  18. GRB 060428B: spectroscopy
  19. GRB 060502B: optical observations
  20. GRB 060502B MDM Follow-up Observation
  21. GRB 060502b: Gemini imaging and spectroscopy
  22. GRB060502A, optical observation
  23. GRB 060502B: Swift/UVOT upper limits
  24. GRB 060502A: Swift/UVOT source detection
  25. GRB 060502B: MDM Optical Observation
  26. GRB060502B: Swift XRT Team refined analysis
  27. Short GRB 060502B: Tautenburg Observation
  28. GRB 060502A: TTT Observations
  29. GRB060502B: correction to XRT position
  30. GRB 060501: P60 Observations and Candidate Retraction
  31. GRB 060502B: Xinglong optical observation
  32. GRB 060502B: MASTER optical observations
  33. GRB 060502B: Swift detection of a short burst
  34. GRB060502: Swift-XRT refined analysis
  35. GRB060502: Gemini spectroscopy
  36. GRB 060502: APO Spectroscopic Observations
  37. GRB060501: Swift UVOT followup observations
  38. GRB060502: Super-LOTIS Observations
  39. GRB 060502: P60 Afterglow Confirmation
  40. GRB 060502: Swift detection of a burst with an optical counterpart
  41. GRB 060501: MDM Observations
  42. GRB060501: P60 imaging and afterglow candidate
  43. GRB060501: Swift XRT position
  44. GRB 060501: Swift detection of a burst
  45. GRB060428B: optical observation
  46. GRB060428B: possible detection of an optical counterpart by Swift/UVOT.
  47. GRB 060428B: MDM Observations
  48. GRB060428B: Swift XRT Team refined analysis
  49. GRB 060428B: KAIT observations
  50. GRB 051117A: Bright host galaxy not confirmed
  51. GRB060428A: Swift/UVOT observations.
  52. GRB 060428b : Kiso R-band limit
  53. GRB 060428b: Optical afterglow candidate
  54. GRB060428A: Swift XRT Team refined analysis
  55. GRB 060428B: Swift detection of a burst
  56. GRB 060427: NIR observations
  57. GRB 060428: Swift detection of a burst
  58. GRB 060427: NOT observations
  59. GRB 060427: Swift/UVOT upper limits.
  60. GRB060427: Swift XRT Team refined analysis
  61. GRB060418: Swift XRT Team Further Refined Analysis
  62. GRB 060427: Swift detection of a burst
  63. GRB060424: optical afterglow detection
  64. GRB060418: Further Analysis of MIKE Spectroscopy
  65. GRB 060424: Swift detection of a burst
  66. OT 060420: Likely Not a New Cosmic Transient
  67. Swift-BAT detection of Mrk 421
  68. OT 060420: CONCAM detection of a candidate new magnitude 5 optical
  69. GRB060421: Swift/UVOT observations
  70. GRB 060421: Swift-XRT refined analysis
  71. GRB060418: optical observations
  72. Konus-Wind observation of GRB 060418
  73. GRB(?)060421:MASTER optical limit
  74. GRB(?)060421 : XRT position
  75. GRB(?) 060421: Swift detection of a burst
  76. Erratum of GCN 4983 for GRB 060418 IR follow-up
  77. GRB 060418 : IR afterglow observations
  78. GRB 060418 : Lulin Optical follow-up
  79. GRB 060418: JHKs PAIRITEL Observations of Afterglow
  80. GRB 060418: Radio Observations
  81. GRB060418, BVRcIc field calibration
  82. GRB060418: Swift/UVOT Observations
  83. GRB060418: Optical Observations
  84. GRB 060418: FRAM early afterglow observation
  85. GRB 060418: Refined Analysis of the Swift-BAT burst
  86. VLT/UVES observations of GRB060418
  87. GRB060418: Swift XRT Team Refined Analysis
  88. GRB 060418, SMARTS continuing afterglow observations
  89. GRB 060418: PROMPT Detections
  90. GRB 060418, SMARTS optical/IR afterglow observations
  91. GRB060418: Magellan/MIKE Spectroscopic Redshift
  92. GRB060418 : LT optical afterglow observation
  93. GRB 060418: REM candidate afterglow
  94. GRB 060418: Swift detection of a burst with bright x-ray and optical afterglow
  95. GRB060413: Swift/UVOT upper limits
  96. GRB 060413: REM NIR Observations
  97. SGR 1900+14: Swift detection of an outburst
  98. GRB 060413: Watcher UBVR observations
  99. GRB 060413: XRT refined analysis
  100. GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data

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